聚氨酯/纳米银抗菌材料的原位可控聚合法制备及构效关系研究

Polyurethanes (PUs) have excellent blood compatibility, so they are irreplaceable materials for the production of cardiovascular artificial organs. As a kind of antibacterial materials, nano silvers have high performance of antibiosis and little resistance to drugs, which are mainly used to inhibit bacterial reproduction on the surface of PUs in clinical applications, so as to avoid surgical infections and medical accidents. However, sometimes polyurethane / nano silver composite materials cannot behave as well as expected because PUs are often obtained with step polymerization and their molecular structure is nonuniform. Moreover, the adhesion strength of PUs and nano silver is not often strong enough to avoid the loss of nano particles when the composite materials are built, whcih leads to high biotoxicity. In this project, new antibacterial PUs are designed to solve the problems above. Firstly, a special polyurethane monomer is synthesized, in which both ends of the monomer are hydroxyl groups and the middle is blocked isocyanate groups with uretidione. Then, according to the induction of monomer solubility, step polymerization can be changed into chain-growth polymerization, and the controlled / “living” polymerization is carried on from the surface of nano silver; Antibacterial PUs with controllable structure is obtained by adjusting molecular weight, molecular weight distribution and cross-linking degree; Influence factors and laws of antibiosis are investigated, so as to determine the quantitative relationship between molecular structure and antibacterial activity. Two key technical problems in the research field of polyurethane / nano silver composite materials will be solved, and a new idea is proposed to guide the molecular structure adjustment of stepwise polymer, such as PUs.

聚氨酯材料具有优异的血液相容性，是制造心血管类人工器官的不可替代的材料。纳米银具有抗菌性好、不易产生抗药性等优点，在临床应用时可抑制聚氨酯表面的细菌，避免手术感染和医疗事故。但是，目前的聚氨酯/纳米银复合材料依靠逐步聚合法制备，很难做到结构均一、可控，致使其应用效果不佳。另外，构筑材料时纳米银与聚氨酯间的结合力往往不够牢固，纳米粒子易泄漏，导致生物毒性。基于以上背景，本课题提出首先设计合成两端为羟基、中间为脲二酮结构的特殊聚氨酯单体，然后以单体的溶解性为诱导把逐步聚合转变为链式聚合，在纳米银表面进行原位可控/活性聚合反应；通过调节聚氨酯的分子量、分子量分布、交联度等结构因素，获得高效、低毒的聚氨酯抗菌材料；明确影响抗菌性能的因素和规律，建立分子结构与抗菌性能的定量关系。本研究将解决聚氨酯/纳米银复合材料研究领域的关键性技术难题，也为聚氨酯等逐步聚合物的分子结构调控提供了新的思路。

聚氨酯是一类重要的医用高分子材料，具有优异的血液相容性、良好的生物稳定性和力学性能，尤其适合制造人工血管、人工心脏、介入导管等血液接触器件，在心血管疾病的治疗中具有不可替代的作用。目前，植入/介入式医用高分子材料的最大问题是，临床应用时细菌易粘附于表面并形成生物膜，从而引起感染、导致手术和医疗事故。因此，获得抗菌性好、安全性高的医用高分子材料，成为当今医学亟待解决的问题，也是化学、材料学、生物学等传统学科的交叉领域的研究热点。. 本项目在深入研究纳米银的合成与表面修饰、聚氨酯的合成反应的基础上，在纳米银表面接枝聚氨酯分子，制备出结构可控的聚氨酯/纳米银复合材料，并结合材料的结构鉴定、表面分析、抗菌实验等来评价其性能，最终获得抗菌性好、安全性高的聚氨酯/纳米银医用高分子材料。主要研究结果如下：.(1)合成出脲二酮封闭的聚氨酯单体，研究了该类特殊单体的聚合反应规律和聚合机理，确定了温度、溶剂、时间、催化剂等因素对聚氨酯合成反应动力学的影响。.(2)研究了纳米银的合成与表面修饰，提出用可逆共价键交联的手段控制纳米银的尺寸与聚集体结构，进而制备出抗菌性能可控的纳米银抗菌材料，研究了可逆反应温度、单体配比等对纳米银表面修饰率和抗菌性能的影响规律。.(3)通过卡宾化学实现聚合物的表面修饰，并与异氰酸酯进行进一步反应，进而附载过氧化氢制备出抗菌高分子材料。在此基础上，制备出聚氨酯/纳米银抗菌材料，研究了材料的Ag+释放性质和抗菌性能。. 本项目的相关研究及其成果丰富了纳米材料的合成与表面修饰、聚合物的可控聚合方法等领域的研究内容，对聚氨酯/纳米银抗菌材料的研究与应用具有重要的借鉴意义。另外，培养硕士研究生3名，发表研究论文16篇(SCI论文13篇)，申请国家发明专利6项。